Monsanto claims that Pioneer used the technology to develop its Optimum AQUAMax corn, intended for use in water-starved areas, and that it plans to expand the technology to China. Monsanto is seeking an injunction and monetary damages.

DuPont spokesman Dan Turner denied the claims, saying in a written statement that “Monsanto continues to use litigation in an attempt to limit Pioneer from being an effective competitor. This tactic has not worked in previous cases, and it will not work in this matter.”

The lawsuit is just the latest instance of legal sparring between the rival companies. In 2009, Monsanto sued DuPont for allegedly infringing patents on herbicide-resistant seeds. And in 2011, the chemical giant fired back with its own lawsuit, claiming that Monsanto infringed DuPont patents for “enhancing the vigor of maize seed.”

For the victor, though, all those legal fees will be worth it: Bloomberg reports that U.S. farm net income may reach $91.7 billion in 2012, the second-highest total on record.